1. Field of the Invention
The invention relates to transient suppression circuits, and, in particular, to a circuit for suppressing transients or overshoot during turn-on/turn-off of a light emitting diode, such as a diode laser.
2. Prior Art
Optical feedback for regulating the output of diode lasers of, e.g., the double heterostructure gallium arsenide type, is well known. For example, d'Auria et al, U.S. Pat. No. 3,996,526, disclose an optical radiation generator which enables a linear light response to be obtained as a function of an electrical signal through the utilization of a current negative feedback loop. DeLoach, Jr. et al, U.S. Pat. No. 3,946,335 disclose a stabilization circuit for radiation emitting diodes which ensures that the radiated output does not exceed a critical value. Brackett et al, U.S. Pat. No. 4,109,217, disclose a stabilization circuit for junction lasers which is in many respects similar to the circuit disclosed by DeLoach, Jr. et al. Shuey, U.S. Pat. No. 3,898,583, discloses a laser stabilization technique in which the output power level of the laser is stabilized at a predetermined set point by a feedback control circuit.
A difficulty with all of the prior art optical feedback circuits is that in starting up or turning off a laser optical feedback power supply, transients or overshoot can occur even if the duration of such transients or overshoot is in the nanosecond range. Consequently, considerable damage, if not destruction, to the diode laser can occur.